The invention relates to dining and/or serving cutlery made of a steel material which is formed from a ferritic core with an essentially martensitic boundary layer. In the case of the dining and/or serving cutlery of the invention, the surface hardness of the boundary layer, determined according to the hardness test according to Vickers HV 3, is thereby greater by 30 to 300% than the lowest hardness of the core, likewise measured according to Vickers HV 3.
In the case of dining and/or serving cutlery, in particular in the case of knives, the basic material of the blade which usually comprises steel normally is hardened by a heat treatment in order to improve the cutting ability and the edge-holding property. The type of heat treatment thereby depends also upon the steel which is used, i.e. whether a low-alloy steel or a high-alloy steel is used.
There are thereby possible basically as heat treatment methods standard methods, such as e.g. a temperature treatment in a furnace. The hardening temperature which must be used for such processes, thereby depends upon the type of steel and can be above 1000° C.
Furthermore, hardening methods have also become known already in the state of the art, in which hardening is implemented by means of a laser beam and/or electron beam.
However it has now been shown in practice that these heat treatment methods and/or the other hardening methods mentioned above with respect to dining and/or serving cutlery do not always lead to satisfactory results. The main reason resides in the fact that, as a result of the above-mentioned hardening methods, generally complete hardening throughout of the steel material is achieved, however the usability required in total for dining and/or for serving cutlery then suffering in such a manner that the individual parts, e.g. a knife or a fork, are impaired in particular in their elastic properties. It has been shown furthermore that, in many cases, the surface hardness which can be achieved consequently is also not sufficient to prevent scratching of the dining and/or serving cutlery in constant use. In some cases, rusting of the surface was also detected.
A hardening method of a martensitic steel (ASI 410) is known from Corrosions Science 48 (2006) 2036-2049 by C. X. Li.
Therefore there is still a great requirement to improve dining and/or serving cutlery such that a high elasticity is present also for long term use, with simultaneously excellent surface properties with respect to scratch resistance and corrosion resistance.